Developmental homology between man and animal Essay

According to Owen R (1848) as cited in one of the lecture notes, homology can be defined as the structural similarities found in species. According to him the organisms had a common ancestor hence a common plan was used to create them. For instance, proteins have a universal genetic code in all species. It is believed that the common ancestor had a similar genetic code hence the premise that species such as man and animal had a common ancestor. This has been used in the explanation of why animal and man have some similar physiological processes such as respiration and reproduction. Man and animal have been found to have similar plasma membrane. The plasma membrane has a phospholipids layer that is similar in both species hence strengthening the theory that man and animal have a common ancestry. Man and frog for instance have pentadactyl limbs. These are five digit limbs hence providing physical evidence of this common ancestor. Towels J and Nelson P. (1997), argued that before Darwin came into the picture, homology was morphologically defined using intelligent designs. It is then cited that Darwin modified the homology concept by introducing theories about common ancestry hence making it possible to understand the theory of homologous evolution. It rendered the intelligent design impossible. Acccording to findings found in the textbook Accuracy Society Organization it is argued that before homology came into the picture, the argument about the possibility of species coming from a common ancestor was not even on the table. According to Szarki (1949), Darwin only introduced the basics about homology and then many scientists were able to pick it from there and modify the concepts. According to research carried out by Geosciences Research Institute (1976), Man and animal were related structurally, physiologically, biochemically and embyologically. This is a homologous trait that supports the theory of man and animal originating from a common ancestor. According to an article in â€Å"Was Darwin Right? † website, evolution biologists argued that the homologous theory was the most powerful source of evidence of evolution since 1859. According to Jones E S (2003-2006), differences between man and ape are not explained. Scientists only argue about the issue of common ancestry. Evolution is basically seen as a fact and not a theory. According to information gathered from Agnosticism/atheism article, homologous structures enabled scientists and evolution biologists to trace the evolution tree of different species. Structural similarities The homologous limbs found in man and animal enabled to be classified as animals in general. This illustrated that they originated from a common ancestor hence explaining the homologous evolution theory. This illustrated that the pattern of bones in the hands of man and the wings of the bat were similar but played different roles which went on to confirm the theory of homologous evolution. It is believed that they had to come from the same ancestor for them to show such similarities. A good example is in a family where children look exactly like their parents. Similarity in development of the embryo. The embryos of both man and animal have been found to develop in a similar pathway hence lending weight to the theory of homologous evolution. Physiological pathways Man and animal have been found to share physiological processes hence the argument that they have a common ancestor. According to Fiscer W F, animals have been found to share physiological processes such as cell respiration, the generation of energy, and even the growth process. (p. 372). This argument basically focuses on the day to day physiological processes such as breathing and the generation of energy. Man and animal have structures that have a similar function hence enabling them to breath in a similar manner. It is believed that the breathing process of man and chimpanzee is indistinguishable. This fact is also used to give credence to the theory of homologous evolution. In addition, their growth and reproductive processes are also similar. Both man and animal have different gestation periods but of similar nature. It takes nine months for man to give birth while in some animals like elephants it takes two years to do the same. They share similar reproduction process and it also involves the embryo. Man and animal have been found to have milk glands in their sytem. this explains why after birth they are able to breastfeed their young ones. The young one of man and animals such as cow always suck milk from their mother’s tits. This again points to likelihood of a common ancestry and this gives even more weight to the theory of homologous evolution. These physiological factors are commonly found in man and animals. They also use related metabolic pathways in the process of generating energy. The liver is seen as the organ that plays a role in the production of energy in man and animal. The process of glycolysis takes place in the liver hence leading to the generation of energy. Information gathered on Glycolysis describes it as process that takes place in prokaryotes and eukaryotes. According to research done on Metabolic Pathways, chemical reactions were found to be taking place in cells hence the Biochemical relationship. The structures and functions of the cells found in man and animal are found to be similar. This can be illustrated by the presence of chromosomes which are found in deoxyribonucleic acid in both man and animal. The organism’s structure and functions depend on DNA and is determined by the genetic code located in the DNA molecule. The classification system always put homologous organisms close together. Darwin as cited by Wells J (2000) was able to explain the evolution theory using the homologous trait found in different organisms. Aristotle, as cited by Wells J (2000) had earlier noticed that different organisms had the same similarities in that they performed the same functions. The different organisms had functional similarities. He also noticed the structural similarities between different organisms. The structures had similar patterns but were able to perform different functions. This is described as homologous evolution theory and it is the most preferred theory used in explaining evolution. Similarly, forelimbs of both man and animal have been found to have a similar pattern bone patterns yet they perform different functions. Man uses his hands to grasp things while a bat uses its wings to fly. The wings found in bats and the hands of man have similar bone structure hence explaining the evolution theory efficiently. There also skeletons have similar features. Even if they have structural similarities that perform different functions, they are regarded as warm blooded mammals and they also have the ability to produce milk. All these facts point to the homologous evolution. Man and animals have different external appearances but their forelimbs are found to be homologous. Homolgous trait was thus defined as a trait of different organisms which have a common ancestor. It went on to explain that man and animal were of the same ancestry even if their forelimbs performed different functions. Similarities in strictures between man and animal According to study published by the â€Å"Answers in Genesis† Organization, homology has been used by botanists to describe organisms with similar structures. A good example is the pattern of bones in the forelimbs man and animal are similar but they conduct different functions. Various questions have been raised about the similarities in the pattern of the bones. One of the possible theories is that man and animal do have a common ancestor. The bones found in arms of humans have a similar structural pattern with bone found in the wings, of a bat. This is described as homologous trait even if they serve different functions. These similarities mean that they have a common ancestor hence explaining the developmental homology between man and animal. They even argue that they were created using a common plan hence the similarities in structures. The hand of a human and that of a chimpanzee are classified as homologous structures. Relationship of blood groups in man and animal Darwin as cited by Sohail K suggested that man and animal also have similar behaviors. The children of human beings always play a lot more so when they feel happy and are healthy. The young and healthy animals who feel happy also play a lot and they can seem to fight sometimes. A good example is that illustrated by puppies or kittens. Puppies and kittens are found to be very playful. They both show that they can be able to be happy and enjoy good life and they can be able to play. These common behaviors found in both man and animal further provides evidence of homologous evolution. Animals like humans can also be sad and afraid. This can be illustrated by the way they both react when in danger. Their muscles tremble and the heart beat faster hence the reason why they always flee from danger. Animals also feel sad when they lose a dear member of the family and most take care of the offspring(s) left behind. Darwin as cited by Sohail K suggested that both man and animal had a similar embryo. Similarities in the brain capacity of man and animal was also put into perspective hence further confirming the homologous evolution theory this illustrates that both man and animal share mental functions. These facts illustrate that both man and animal had a common ancestor hence the similarities in structures and behaviours. These traits are only found in organisms that share a common ancestor. Physiological processes Both man and animal share physiological function such as eating, digestion and so forth. They both have to put food through their mouth which is a common trait. According to the article published by Science and Evolution, man and some animals were found to have similar organs in their body. Some of the organs include the liver, appendix, and also the intestines. This illustrates that they were from a common ancestor hence a solid argument about homologous evolution. The liver play a similar role in both man and animal in the process glycolysis. Glycolysis pathway has been found in both man and animal hence further providing evidence of them having a common ancestor in the family tree. The study starts by illustration that homologous structures basically mean similar structures hence very important when it comes to the topic about evolution. Fossils. According to an article on Fossils and Evolution, fossils have been defined as prehistoric remains of organisms. As cited by Gore J. W. P, William, Smith in the 17th century was able to discover that fossils piled in sedimentary rocks in a vertical order in the whole world. This was an important clue in the explanation of the process of evolution. The fossil species were able to appear and disappear in different times. This illustrated that those species used to look for favorable environments in order to survive. They move from unfavorable places to those places tat they could survive. The recovered fossils of both man and animal have been found to be similar in appearances. Some animal’s fossils showed that they had a dental formula similar to those of humans hence providing evidence of homologous evolution in man and animal. The rocks found in the surfaces the earth have been found to be having animal remains. These animal remains have been described as fossils. These fossils have been used to explain and prove that there is a similarity between animal and man. They have been able to use these fossils evidences in order to determine the pattern of evolution. The fossils have been used to explain homologous evolution which suggested that animal and man had similar structures which performed different functions hence shared a common ancestor. According to research findings published in â€Å"All about Creation† article (2002-2008), fossils have been found to be buried in a sequential manner. This enabled the scientists to explain effectively the theory of evolution. Molecular homology According to the study published by the University of Waikato, it was found that living organisms have similar genetic code pointing again to a common ancestor. This evidence can also be used in man and dog. They have the same genetic codes . The bases responsible for molecular homology include are adenine, guanine, cytosine, and thymine. These bases are found in man and animals. These bases are able to encode instructions using a chemical language hence making the organisms respond to the instructions such as reproduction. The bases combine hence instructing the cells responsible to use amino acids to manufacture proteins . these manufactured proteins enable the cells to function. Without the proteins the organism has no life in it. The similarities in the genetic codes hence provide evidences of man and dog having a common ancestor. Fossils were used by scientists to prove that organisms changed from time to time. They did this by examining them and trying to determine their ages. This was very important in the study of evolution. They compared the theories of common ancestry, the structural similarities, the biochemical similarities, and the way the organisms developed. They were able to prove that man and animals had a common ancestor even if the organisms changed from time to time. They argued that man and bat had a common ancestor. The forelimbs of man and bat have similar bone patterns hence possible prove of common ancestry. They even used biochemistry to argue illustrate their theories. They singled out cytochrome c, which is a protein found in both man and animal. cytochrome c assists in anaerobic respiration. The similarity in cytochrome c in both man and animal helps in explaining the theory of homologous evolution. It illustrates that man and animal have a common ancestor. Conclusion According to evidence illustrated in this research paper, conclusions can be made regarding the developmental homology in animal and man in relation to evolution. There are similarities in structures in man and animal. These structures do perform different functions but they have similar bone pattern. An example to support the claim is the similar bone pattern in the hands of man and the wings of bat. They have a similar pattern but serve different functions. Man uses hand to grasp while bat uses wings to fly. This illustrates that man and animal have a common ancestor hence supporting the process of homologous evolution in man and animal. They also have similar physiological processes such as reproduction and respiration. Similarities in reproduction can be explained by the similarities in the embryos of man and animal and also by the different gestation periods they have and their ability to produce milk. Man, cow and dog can be able to produce milk for their young ones. This has been seen happening physically when mothers are breastfeeding their babies. Young calves have also been seen sucking tits of cows for milk. Man and cow plus other animals have mammary glands which are responsible for the production of milk. This fact enabled many evolution biologists put their arguments on the table about the possibility of man and animal having a common ancestor and they were able to convince many with their argument. Man and animal are believed to have a single ancestor hence the similarities in some of the characteristics. This makes the theory of them having a common ancestor possible. Man and animal have similar physiological pathways that produce energy and also their breathing pattern is the same. Chromosomes have also been found in the DNA of man and animal hence chromosomal similarities hence high chances of them having a common ancestor. The study has also led to the conclusion that man and animal could be having same blood groups. This is due to detection of A and B antigens in the saliva of horses. Fossils have also been used to explain homologous evolution in man and animal. Different fossils have been discovered with the almost similar formula as that of man. The dental formula of man and dog differ slightly hence the possibility of them having a common ancestor. Man and animal have also been found to have similar behaviours. When still young they play a lot and they are always happy when they enjoy life. both man and animal become sad when hey lose a loved one and the always take the responsibility of taking care of the orphans . these similarities lead to the conclusion that there is a man and animal have a common ancestor. Homologous structures are therefore very important in the illustrations of evolution theory. References Agnosticism/atheism retrieved on December 6, 2008 from http://atheism. about.com/library/glossary/evolution/bldef_analogous. htm All about creation organisation. Fossil Evidence for Evolution retrieved on December 6, 2008 from http://www. allaboutcreation. org/fossil-evidence-for-evolution-faq. htm Brand R (1976). Geoscience Research Institute. Homologies. Retrieved on December 6, 2008 from http://search. bio-medicine. org/more. asp? m=evolution Evolution. Evidences from living organisms retrieved on December 6, 2008 from http://bioweb. cs. earlham. edu/9-12/evolution/HTML/live. html Fischer F. W. P. (1997) Trace element in both animal and man—9. USA. NRC Research